Study may help better cool hybrid cars

WEST LAFAYETTE, Ind., Sept. 22 (UPI) -- Purdue University researchers say they have perfected an understanding of precisely how fluid boils in tiny "microchannels" in hybrid and electric cars.

That discovery, said the researchers, has led to formulas and models that will help engineers design systems to cool high-power electronics in electric and hybrid cars, aircraft, computers and other devices.

The new type of cooling system will be used to prevent overheating of devices called insulated gate bipolar transistors -- high-power switching transistors used in hybrid and electric vehicles.

Allowing a liquid to boil in cooling systems dramatically increases how much heat can be removed, compared to simply heating a liquid to below its boiling point, said Professor Suresh Garimella, who led the research. However, boiling occurs differently in tiny channels than it does in ordinary size tubing used in conventional cooling systems.

"One big question has always been, where is the transition from macroscale boiling to microscale boiling?" doctoral student Tannaz Harirchian said. "How do you define a microchannel versus a macrochannel, and at what point do we need to apply different models to design systems? Now we have an answer."

The findings will be detailed in a research paper by Garimella and Harirchian and a keynote address to be presented by Garimella during an October scientific conference in Leuven, Belgium.